Semiconductor device and manufacturing method thereof, and electronic device including the semiconductor device

ABSTRACT

The present disclosure provides a semiconductor device and a manufacturing method thereof, and an electronic device including the semiconductor device. The semiconductor device includes: a substrate; an active region including a first source/drain region, a channel region and a second source/drain region stacked sequentially on the substrate and adjacent to each other; a gate stack formed around an outer periphery of the channel region; and spacers formed around the outer periphery of the channel region, respectively between the gate stack and the first source/drain region and between the gate stack and the second source/drain region; wherein the spacers each have a thickness varying in a direction parallel to a top surface of the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the Chinese Patent Application No.201911244799.8 filed on Dec. 6, 2019, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a field of semiconductor technology,and in particular to a vertical semiconductor device and a manufacturingmethod thereof, and an electronic device including the semiconductordevice.

BACKGROUND

Horizontal semiconductor device (such as metal oxide semiconductor fieldeffect transistors (MOSFET)) has source electrode, gate electrode anddrain electrode arranged in a direction substantially parallel to a topsurface of a substrate (the horizontal direction), and thus has theproblems that a size of the device in the horizontal direction is noteasy to reduce and it is not conducive to improve an integration densityof an electronic device or chip. The use of vertical semiconductordevice may further improve the integration density. In the verticalsemiconductor device, the source electrode, gate electrode and drainelectrode of the transistor are arranged in a direction substantiallyperpendicular to the top surface of the substrate (the verticaldirection), thus the vertical device has more space for optimization inthe vertical direction and the size may be reduced more easily in thehorizontal direction.

As the size of the vertical device shrinks and the integration densityincreases, it becomes more and more difficult to form a dielectricspacer between the gate electrode and the source/drain region, which maycause an increase of parasitic capacitance, thereby causing a negativeeffect on performance of the device and integrated circuit.

SUMMARY

In view of this, the present disclosure provides a semiconductor deviceand a manufacturing method thereof to at least partially solve theabove-mentioned problems.

According to a first aspect of the present disclosure, there is provideda semiconductor device, including: a substrate; an active regioncomprising a first source/drain region, a channel region and a secondsource/drain region stacked sequentially on the substrate and adjacentto each other; a gate stack formed around an outer periphery of thechannel region; and spacers formed around the outer periphery of thechannel region, respectively between the gate stack and the firstsource/drain region and between the gate stack and the firstsource/drain region; wherein the spacers each have a thickness varyingin a direction parallel to a top surface of the substrate.

According to a second aspect of the present disclosure, there isprovided a method of manufacturing a semiconductor device, including:forming a first material layer and a second material layer sequentiallyon a substrate; defining an active region of the semiconductor device onthe substrate, the first material layer and the second material layer,wherein the active region comprises a channel region; forming spacersaround an outer periphery of the channel region, respectively at setpositions of the substrate and the second material layer; forming afirst source/drain region and a second source/drain region on thesubstrate and the second material layer respectively; and forming a gatestack around the outer periphery of the channel region; wherein thespacers each have a thickness varying in a direction parallel to a topsurface of the substrate.

According to a third aspect of the present disclosure, there is providedan electronic device including an integrated circuit formed by theabove-mentioned semiconductor device.

According to embodiments of the present disclosure, by providing thespacer between the overlapping gate stack and source/drain region, theparasitic capacitance between the gate stack and the source/drain regionis effectively reduced, which improves switching performance of thesemiconductor device. The spacer is formed by oxidation treatment andetching steps and do not need to go through a complicated process, thusthe production process is simplified and the production cost is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentdisclosure will be more apparent through the following description ofembodiments of the present disclosure with reference to the drawings, inwhich:

FIG. 1 shows a schematic structural diagram of a semiconductor deviceaccording to some embodiments of the present disclosure;

FIGS. 2-12 show schematic diagrams of a process of manufacturing asemiconductor device according to some embodiments of the presentdisclosure; and

FIGS. 13-16 show schematic diagrams of a process of manufacturing asemiconductor device according to another embodiment of the presentdisclosure.

Throughout the drawings, the same or similar reference numerals indicatethe same or similar composite parts.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described below withreference to the drawings. It should be understood, however, that thesedescriptions are merely exemplary and are not intended to limit thescope of the present disclosure. In addition, in the followingdescription, descriptions of well-known structures and technologies areomitted to avoid unnecessarily obscuring the concepts of the presentdisclosure.

Various schematic structural diagrams according to the embodiments ofthe present disclosure are shown in the drawings. The figures are notdrawn to scale. Some details are enlarged and some details may beomitted for clarity of presentation. The shapes of the various regionsand layers shown in the figures, as well as the relative size andpositional relationship thereof, are only exemplary. In practice, theremay be deviations due to manufacturing tolerances or technicallimitations, and those skilled in the art may additionally designregions/layers with different shapes, sizes and relative positionsaccording to actual needs.

In the context of the present disclosure, when a layer/element isreferred to as being “on” another layer/element, the layer/element maybe directly on another layer/element, or there may be an intermediatelayer/element between them. In addition, if a layer/element is located“on” another layer/element in one orientation, the layer/element may belocated “under” another layer/element when the orientation is reversed.

FIG. 1 shows a schematic structural diagram of a semiconductor deviceaccording to some embodiments of the present disclosure. As shown inFIG. 1, a vertical semiconductor device according to the embodiments ofthe present disclosure may include a substrate 100 and a firstsource/drain region 101, a channel region 102 and a second source/drainregion 103 stacked sequentially on the substrate 100 and adjacent toeach other. The first source/drain region 101, the channel region 102and the second source/drain region 103 constitute a columnar activeregion of the device. A gate stack 104 is formed around an outerperiphery of the channel region 102. Therefore, a gate length of thedevice is related to a thickness of the channel region 102, and may bedetermined by the thickness of the channel region 102 without relying onetching. In this way, processing time may be saved, and the gate lengthof the device may be more effectively controlled by controlling thethickness of the channel region 102. According to the embodiments, thechannel region 102 may be formed by a growth process such as epitaxialgrowth, and thus the thickness of the channel region 102 may becontrolled well, and accordingly the gate length of the device formedmay be controlled well.

In the vertical semiconductor device structure shown in FIG. 1, the gatestack 104 includes two parts, including a gate dielectric layer 1041 anda gate conductor layer 1042. The gate dielectric layer 1041 generallyincludes a high-k gate dielectric (such as SiO₂ and HfO₂) or oxide, andthe gate conductor layer 1042 generally includes a gate conductor formedof a metal material. As shown in FIG. 1, the gate dielectric layer 1041is located between the gate conductor layer 1042 and the firstsource/drain region 101 and between the gate conductor layer 1042 andthe second source/drain region 103, which is equivalent to that acapacitance is formed in the overlap portion of the gate stack 104 andthe first source/drain region 101 and in the overlap portion of the gatestack 104 and the second source/drain region 103, that is, a parasiticcapacitance exists in the overlap portion of the gate stack 104 and thefirst source/drain region 101 and in the overlap portion of the gatestack 104 and the second source/drain region 103. The parasiticcapacitance may affect the build-up time of the internal current of thesemiconductor device, which is manifested as an increase in a delay oftime for turning on the semiconductor device, thereby affecting theswitching performance of the device.

According to some embodiments of the present disclosure, spacers 105 areprovided around the outer periphery of the channel region 102,respectively between the gate stack 104 and the first source/drainregion 101 and between the gate stack 104 and the second source/drainregion 103. The spacers 105 increase the distance of the capacitanceformed between the gate stack 104 and the first source/drain region 101and between the gate stack 104 and the second source/drain region 103,thus reducing the parasitic capacitance in the overlap portion of thegate stack 104 and the first source/drain region 101 and in the overlapportion of the gate stack 104 and the second source/drain region,thereby accelerating the build-up of the internal current of thesemiconductor device, reducing the delay of the time for turning on thedevice, and improving the switching performance of the device.

As shown in FIG. 1, the spacer 105 has a surface exposed on the outerperipheral surface of the active region. The spacer 105 extends from theexposed surface to the inside of the active region, and the extendedterminal does not enter the inside of the channel region 102. That is tosay, the spacers 105 are located outside the outer periphery of thechannel region 102.

As shown in FIG. 1, the spacer has a thickness varying in a directionparallel to a top surface of the substrate 100. According to someembodiments, the spacer 105 has the thickness gradually decreasing fromthe surface exposed on the outer peripheral surface of the active regionto the inside of the active region. According to some embodiments, thethickness of the spacer 105 that gradually decreases is formed byoxidation treatment. According to some embodiments, the spacers 105 maybe formed by performing oxidation treatment on the materials of thefirst source/drain region 101 and the second source/drain region 103.According to some embodiments, the spacer 105 may be formed byperforming oxidation treatment on materials deposited on surfaces of thefirst source/drain region 101 and the second source/drain region 103.Therefore, the spacer 105 includes an oxide.

In other embodiments, the oxide formed may be selectively etched to forma trench where the original oxide is located, and a material with a lowdielectric constant may be used to fill the trench formed so as to formthe spacer 105. Due to the use of material with low dielectric constant,the spacer 105 formed may have better dielectric properties than oxide,which may significantly reduce the parasitic capacitance between thegate stack 104 and the first source/drain region 101 and between thegate stack 104 and the second source/drain region 103. In someembodiments, a material such as SiC may be used to form the spacer 105.

According to some embodiments of the present disclosure, the firstsource/drain region 101 and the second source/drain region 103 areformed by a diffusion doping process. Doped regions of the firstsource/drain region 101 and the second source/drain region 103 thusformed (shown as the deepened part in FIG. 1) are located in shallowlayers of the surfaces of the source/drain regions (for example, in ashallow layer with a doping concentration of 1E19 cm⁻³˜1E21 cm⁻³). Asshown in FIG. 1, the doped regions of the first source/drain region 101and the second source/drain region 103 formed by diffusion doping extendalong the outer surface of the first source/drain region 101 and theouter surface of the second source/drain region 103, respectively.

According to some embodiments of the present disclosure, the spacers 105are completely located inside the doped regions of the firstsource/drain region 101 and the second source/drain region 103. As shownin FIG. 1, the spacers 105 extend from the surface exposed on the outerperipheral surface of the active region to the inside of the activeregion. A leading edge of the dopant forming the doped regions of thefirst source/drain region 101 and the second source/drain region 103diffuses into the active region, and the leading edge of the dopantexceeds the spacers 105, so that the spacers 105 are completely locatedinside the doped regions of the first source/drain region 101 and thesecond source/drain region 103 formed. This helps to reduce theresistance of the conductive channel.

The spacers 105 have surfaces parallel to the direction of the topsurface of the substrate 100, and the surfaces parallel to the directionof the top surface of the substrate 100 are aligned with an interface Iand an interface I′ respectively. Therefore, according to theembodiments of the present disclosure, a self-alignment of the gatestack 104 with the channel region 102 may be achieved, and aself-alignment of the gate stack 104 with the first source/drain region101 and the second source/drain region 103 may also be achieved, therebyimproving the manufacturing accuracy and performance of the device, andfacilitating mass production of the device.

As shown in FIG. 1, an upper surface of the spacer 105 between the firstsource/drain region 101 and the gate stack 104 is substantially coplanarwith the interface I, and a lower surface of the spacer 105 between thesecond source/drain region 103 and the gate stack 104 is substantiallycoplanar with the interface I′. A bottom surface of the gate stack 104is substantially parallel to the interface I between the material layerforming the channel region 102 and the material layer forming the firstsource/drain region 101, and a top surface of the gate stack 104 issubstantially parallel to the interface I′ between the material layerforming the channel region 102 and the material layer forming the secondsource/drain region 103. Further, a distance between the bottom surfaceof the gate stack 104 and the interface I between the material layerforming the channel region 102 and the material layer forming the firstsource/drain region 101 is substantially equal to a distance between thetop surface of the gate stack 104 and the interface I′ between thematerial layer forming the channel region 102 and the material layerforming the second source/drain region 103.

According to the embodiments of the present disclosure, the time forturning on the semiconductor device and the time for turning off thesemiconductor device may be reduced effectively, thereby improving theswitching performance of the device. In addition, the semiconductordevice according to the embodiments of the present disclosure can beself-aligned during the manufacturing process, which is beneficial tothe mass production of the device.

It can also be seen from FIG. 1 that only the upper portion of thesubstrate 100 is etched, and the lower portion of the substrate 100 mayextend beyond the outer periphery of the upper portion. Such a structuremay facilitate formation of connection of the source/drain regions inthe subsequent process. As shown in FIG. 1, the semiconductor devicefurther includes via holes respectively exposing the gate stack 104, thefirst source/drain region 101 and the second source/drain region 103, inwhich a contact portion 108_1 for connecting the gate stack 104, acontact 108_2 for connecting the first source/drain region 101 and acontact 108_3 for connecting the second source/drain region are formedrespectively. In addition, an isolation layer 106 is further formed on atop surface of a lower region of the first source/drain region 101beyond an outer periphery of an upper region of the first source/drainregion 101. A top surface of the isolation layer 106 is close to(substantially coplanar with) the surface of the first source/drainregion 101 adjacent to the channel region 102. An interlayer dielectriclayer 107 is further formed on the top of the semiconductor device forisolation and protection of the device.

According to some embodiments of the present disclosure, the channelregion 102 may be formed of a single crystal semiconductor material, andthe channel region 102 may include a semiconductor material differentfrom that of the first source/drain region 101 and the secondsource/drain region 103. In this way, it is advantageous to process (forexample, selectively etch) the channel region 102 when defining theactive region, so as to form a recess for embedding the gate stack. Thechannel region 102 may be formed by an epitaxial growth process or amolecular beam epitaxy (MBE) process. The epitaxial growth process ispreferably a low temperature epitaxial growth process.

The present disclosure may be presented in various forms, some examplesof which will be described below.

FIGS. 2-12 show schematic diagrams of a process of manufacturing asemiconductor device according to some embodiments of the presentdisclosure. The process will be described in detail below with referenceto the drawings.

As shown in FIG. 2, the substrate 100 is provided. The substrate 100 maybe in various forms, including but not limited to bulk semiconductormaterial substrate such as bulk Si substrate, semiconductor-on-insulator(SOI) substrate, compound semiconductor substrate such as SiGesubstrate, and the like. For ease of description, in the embodiments ofthe present disclosure, a bulk Si substrate is taken as an example fordescription. The substrate 100 may be used to form the firstsource/drain region 101.

On the substrate 100, a first material layer 1001 and a second materiallayer 1002 may be formed sequentially. In a specific embodiment, thefirst material layer 1001 and the second material layer 1002 may beformed sequentially by an epitaxial growth process.

According to some embodiments, the first material layer 1001 is firstformed on the provided substrate 100 by epitaxial growth. The firstmaterial layer 1001 may be used to form the channel region 102. Thethickness of the channel region 102 may be used to define the thicknessof the gate stack (i.e., the gate length). In some embodiments of thepresent disclosure, the first material layer 1001 may be a SiGe materiallayer with a thickness of about 10 nm˜100 nm and a Ge content of about10%˜40%. Then, the second material layer 1002 is formed on the firstmaterial layer 1001 by epitaxial growth, and the second material layer1002 may be used to form the second source/drain region 103. In someembodiments of the present disclosure, the second material layer 1002may be a Si material layer with a thickness of about 30 nm˜100 nm. Itshould be noted that the present disclosure is not limited to this. Thetype and thickness of the above-mentioned material layer may be changed.For example, when the above three material layers are formed by anepitaxial growth process, it is only necessary to ensure that the firstmaterial layer 1001 has a larger etch selectivity ratio than thematerial of the substrate 100 and the second material layer 1002.

In some embodiments of the present disclosure, it is preferable to usean epitaxial growth process or a molecular beam epitaxy process to formeach material layer. The epitaxial growth process preferably adopts alow temperature epitaxial growth process. The formation of each materiallayer by an epitaxial growth process can well control the thickness ofthe material layer of the channel region 102. The thickness of thechannel region 102 determines the size of the recess for accommodatingthe spacers and the gate stack, and may be used to performself-alignment of the spacers and the gate stack with the channel region102, thereby improving the processing accuracy of the device. Inaddition, in some embodiments of the present disclosure, the channelregion 102 uses a single crystal semiconductor material, which isbeneficial to reduce the resistance when the device is turned on, andimprove the performance of the device.

Next, the active region of the device may be defined. The active regionof the device includes the first source/drain region 101, the channelregion 102 and the second source/drain region 103. The defining theactive region mainly refers to restricting the shape of the activeregion. Specifically, as shown in FIGS. 3A and 3B (wherein FIG. 3A is across-sectional view, FIG. 3B is a top view, and the line AA′ in FIG. 3Bshows the cutting position of the cross-section), a photoresist (notshown) may be formed on the stack of the substrate 100, the firstmaterial layer 1001 and the second material layer 1002 shown in FIG. 2.The photoresist is patterned into a desired shape by photolithography(exposure and development), and the patterned photoresist is used as amask to perform selective etching (for example, reactive ion etching(RIE)) sequentially on the second material layer 1002, the firstmaterial layer 1001 and a part of the substrate 100. The etchingproceeds to the upper portion of the substrate 100. The etched secondmaterial layer 1002, first material layer 1001 and upper portion of thesubstrate 100 form a column. RIE, for example, may be performed in adirection substantially perpendicular to the top surface of thesubstrate 100, so that the column is also substantially perpendicular tothe top surface of the substrate 100. After the etching is completed,the photoresist is removed.

It can be seen from the top view of FIG. 3B that, in this embodiment,the cross section of the active region is substantially circular, thatis, the outer periphery of the active region is substantiallycylindrical. A radius of the circular cross section may preferably be 10nm˜30 nm. In other embodiments, the active region may have other shapes.When the cross section of the active region is a square, a side lengthof the square may preferably be 10 nm˜30 nm. When the cross section ofthe active region is a rectangular, a width of the rectangle (in thevertical direction of the plane of FIG. 3B) may preferably be 10 nm˜30nm, and a length of the rectangle (in the horizontal direction of theplane of FIG. 3B) is determined by the magnitude of the device current.Such a structure helps to improve the mobility, not only can providesufficient device current, but also can better control a short channeleffect and optimize the performance of the device. Of course, the shapeof the active region is not limited to this, but can be designedaccording to the layout. For example, the cross section of the activeregion may be oval, polygonal, or the like.

Next, as shown in FIG. 4, the first material layer 1001 in FIG. 3A isrecessed inward with respect to the columnar active region (that is, ina direction opposite to the normal direction of the outer peripheralsurface of the columnar active region) so as to form the channel region102. This may be achieved by selectively etching the first materiallayer 1001 relative to the substrate 100 and the second material layer1002. A modifier may be used at least once to form a modified layer on asurface including the surface to be etched, and the modified layerformed may be etched at least once to form a predetermined structure onthe surface to be etched.

According to some embodiments, the entire stack structure formed in theforegoing process steps is first put into a surface modifier. Throughthe reaction between the modifier and the semiconductor material, amodified layer in oxide form is formed on the surface of the substrate100, the first material layer 1001 and the second material layer 1002.If the material of the substrate 100 and the second material are Si, andthe first material is SiGe, SiGe has a faster oxidation rate than Si,and the oxide formed (for example, SiGeO formed on the SiGe surface) iseasier to remove. Generally, after the modified layer is formed, thesemiconductor surface on which the modified layer is formed is cleaned.Then, the modified layer is removed with an etchant and thesemiconductor surface where the modified layer has been removed iscleaned. Since the first material layer 1001 has a faster oxidationrate, the first material layer 1001 forms a recess relative to thesubstrate 100 and the second material layer 1002 after the modifiedlayer is removed. Then, it is checked whether the etching reaches apreset depth. If it has not reached the preset depth, the above processsteps of forming the modified layer with the modifier and etching themodified layer are repeated until the preset depth and etchingrequirement are reached. The method may accurately control the etchingthickness (≤0.5 nm) during semiconductor processing, and also increasethe etching rate. The etched stack structure is shown in FIG. 4, thefirst material layer 1001 recessed inwardly serves as the channel region102 of the device, and the recessed structure surrounds the outerperiphery of the channel region 102.

The modifier used may include but is not limited to liquid or aqueoussolutions of one or a combination of ozone (O₃), potassium permanganate(KMnO₄), potassium dichromate (K₂Cr₂O₇), nitric acid (HNO₃), sulfuricacid (H₂SO₄), hydrogen peroxide (H₂O₂), oxygen-containing gas oroxygen-containing plasma. The etchant used may include but is notlimited to hydrofluoric acid, buffered hydrofluoric acid, BOE,hydrofluoric acid vapor, halogen hydride or vapors thereof. The cleaningagent used may include but is not limited to water, high-puritydeionized water, ethanol, acetone, and the like.

According to other embodiments, the channel region 102 may also beformed by atomic layer etching. Hydrogen (H) ions or helium (He) ionsmay be used to process the first material (for example, SiGe) layer toform the modified layer on the surface of the first material layer.Then, the modified layer is removed by wet etching or using free radicalmaterials (such as NH₃, NF₃, etc. in an active state). Similarly, thesteps of forming the modified layer and removing the modified layer maybe repeated until the recess with a predetermined depth is obtained.

Next, as shown in FIG. 5, the spacers 105 are formed at set positions ofthe top surface of the substrate 100 and the second material layer 1002.In a specific embodiment, a sacrificial layer 1003 is first formed inthe recess formed in FIG. 4. The sacrificial layer 1003 may be formed bydepositing a material layer for forming the sacrificial layer 1003 onthe structure shown in FIG. 4, and then performing etching back such asRIE on the deposited material layer. The direction of etch back issubstantially perpendicular to the direction of the top surface of thesubstrate 100. The sacrificial layer 1003 formed is filled in therecess, and the outer peripheral surface of the sacrificial layer 1003is substantially coplanar with the outer peripheral surface of thecolumnar active region. According to some embodiments, the sacrificiallayer 1003 can be made of a nitride material. In one hand, the use ofnitride material may prevent the sacrificial layer 1003 from beingoxidized in the subsequent oxidation process. If the sacrificial layer1003 is oxidized in the subsequent oxidation process and thus a portionthereof is etched away, the sacrificial layer 1003 will not be able tocompletely fill the recesses, and the spacers 105 formed will be damagedby subsequent processes. On the other hand, the nitride may ensure thatthe sacrificial layer 1003 has an etch selectivity relative to othermaterials in the subsequent process, so that the sacrificial layer 1003may be removed by etching without damage to other structures. However,the present disclosure is not limited to this, and other materials withthe above-mentioned characteristics may also be used.

Next, as shown in FIG. 6, oxidation treatment is performed on the topsurface of the substrate 100 and the outer surface of the secondmaterial layer 1002 so as to form an oxide layer 1004 on the top surfaceof the substrate 100, the outer surface of the second material layer1002, the interface between the bottom 100 and the sacrificial layer1003 and the interface between the second material layer 1002 and thesacrificial layer 1003. According to some embodiments, thermal oxidationor plasma-enhanced oxidation process may be used for oxidationtreatment. According to some embodiments, a thickness of the oxide layer1004 formed may be in the range of 5 nm˜20 nm.

As shown in FIG. 6, when the oxidation treatment is performed on the topsurface of the substrate 100 and the outer surface of the secondmaterial layer 1002, the substrate 100 at the interface between thesubstrate 100 and the sacrificial layer 1003 has a faster oxidation ratebecause there are defects at the interface between the substrate 100 andthe sacrificial layer 1003. Therefore, the oxidation process may advancetoward the inside of the active region faster at the interface, therebyforming an oxide layer 1004 at the interface between the substrate 100and the sacrificial layer 1003. As shown in FIG. 6, the oxide layer 1004formed in this way has a gradually decreasing thickness and has a shapeof a bird's beak when viewed from the cross section shown in FIG. 6.Similarly, since there are defects at the interface between the secondmaterial layer 1002 and the sacrificial layer 1003, the second materiallayer 1002 at the interface between the second material layer 1002 andthe sacrificial layer 1003 has a faster oxidation rate. Therefore, theoxidation process may advance toward the inside of the active regionfaster at the interface, thereby forming the oxide layer 1004 at theinterface between the second material layer 1002 and the sacrificiallayer 1003. As shown in FIG. 6, the cross section of the oxide layer1004 also has a shape of a bird's beak.

Next, the oxide layer 1004 is etched to form the spacers 105 at theinterface between the substrate 100 and the sacrificial layer 1003 andthe interface between the second material layer 1002 and the sacrificiallayer 1003. According to some embodiments, the etching performed here ispartial etching, that is, only a portion of the oxide layer 1004 isetched away. As shown in FIG. 7, by partially etching the oxide layer1004 shown in FIG. 6, only the oxide layer 1004 on the outer surface ofthe active region and the top surface of the substrate 100 is removed,while the oxide layer 1004 at the interface between the substrate 100and the sacrificial layer 1003 and the interface between the secondmaterial layer 1002 and the sacrificial layer 1003 are retained.According to some embodiments of the present disclosure, the unetchedoxide layer 1004 may be used as the spacers 105.

According to the embodiments of the present disclosure, the spacers 105may be obtained by simple oxidation treatment and etching of the oxidelayer formed, which is beneficial to simplify the production process ofthe device and reduce the production cost of the device.

In addition, according to other embodiments of the present disclosure,the oxide layer 1004 may also be completely removed by selectivelyetching the oxide layer 1004 relative to the substrate 100, the secondmaterial layer 1002 and the sacrificial layer 1003. In this way,trenches are formed at the interface between the substrate 100 and thesacrificial layer 1003 and the interface between the second materiallayer 1002 and the sacrificial layer 1003 where the oxide layer 1004 ispreviously filled. Then, the trenches may be filled with a material witha low dielectric constant so as to form the spacers 105 in the trenches.The spacers 105 formed have the same shape as the spacers in theforegoing embodiments, but can reduce the parasitic capacitance moreeffectively due to the use of the material with the low dielectricconstant.

In addition, as shown in FIG. 7, at the interface between the substrate100 and the sacrificial layer 1003 and the interface between the secondmaterial layer 1002 and the sacrificial layer 1003, the spacers 105 arealmost entirely formed inside the substrate 100 and the second materiallayer 1002. In other words, as shown in FIG. 7, the upper surface of thespacer 105 located between the substrate 100 and the sacrificial layer1003 is substantially coplanar with the interface between the substrate100 and the sacrificial layer 1003 (referring to FIG. 1, that is, theinterface I), and the lower surface of the spacer 105 located betweenthe second material layer 1002 and the sacrificial layer 1003 issubstantially coplanar with the interface between the second materiallayer 1002 and the sacrificial layer 1003 (referring to FIG. 1, that is,the interface I′). That is to say, an alignment between the spacersformed and the channel region 102 is achieved. In this way, in thesubsequent process of forming the gate stack 104, the self-alignmentbetween the gate stack 104 and the channel region 102 and theself-alignment between the gate stack 104 and the first source/drainregion 101 and between the gate stack 104 and the second source/drainregion 103 may be achieved based on the spacers 105 formed.

Next, the first source/drain region 101 and the second source/drainregion 103 are formed on the substrate 100 and the second material layer1002 respectively. In a specific embodiment, first, a dopant film isdeposited on the outer surface of the columnar active region at leastincluding the surface of the upper portion of the substrate 100 and theouter surface of the second material layer 1002 shown in FIG. 7. Thedopant film formed surrounds the outer surfaces of the substrate 100,the sacrificial layer 1003, the spacers 105 and the second materiallayer 1002. According to some embodiments, the dopant film may bedeposited by the process such as chemical vapor deposition (CVD), atomiclayer deposition (ALD), or plasma doping. For an n-type semiconductordevice, an n-type dopant film may be used, and for a p-typesemiconductor device, a p-type dopant film may be used. Then, the dopantfilm is used as a solid phase diffusion source, and an annealing processis used to drive in diffusion of the dopant in the dopant film so as toform doped first source/drain region and second source/drain region.Generally, the doped region is a doped area with a doping concentrationof 5E18 cm⁻³˜1E19 cm⁻³. As shown in FIG. 8, the doped region of thefirst source/drain region 101 is formed in a shallow layer of the upperportion of the substrate 100 around the outer peripheral surface of theactive region and in a shallow layer of the top surface of the lowerportion of the substrate 100. The doped region of the secondsource/drain region 103 is formed in a shallow layer of the outersurface of the second material layer 1002. Both the first source/drainregion 101 and the second source/drain region 103 are source/drainregions with a relatively shallow junction depth, which is beneficial toimprove the short channel effect of the device. After the dopingdiffusion process is completed, the dopant film is removed.

According to some embodiments of the present disclosure, when annealingto drive in the diffusion of the dopant film, a process of the diffusionis controlled, so that a leading edge surface of the dopant is diffusedin the first source/drain region 101 and the second source/drain region103 and exceeds the spacers 105 formed. As shown in FIG. 8, the spacers105 are completely located inside the doped regions of the firstsource/drain region 101 and the second source/drain region 103. In thisway, carriers in the first source/drain region 101 and the secondsource/drain region 103 may enter the conductive channel more easily, soas to reduce the resistance of the device and increase the current ofthe device

Next, an isolation layer may be formed around the active region toachieve electrical isolation. As shown in FIG. 9, an oxide may bedeposited on the top surface of the lower portion of the substrate 100,and etching back is performed on the deposited oxide to form anisolation layer 106. The etching back stops at the interface between thefirst source/drain region 101 and the spacer 105 exposed from the outerperipheral surface of the active region. In this way, the top surface ofthe isolation layer 106 formed may be substantially coplanar with theinterface between the material layer forming the channel region 102 andthe material layer forming the first source/drain region 101. Prior tothe etching back, planarization treatment such as chemical mechanicalpolishing (CMP) or sputtering may be performed on the deposited oxide.

In some embodiments of the present disclosure, prior to forming theabove-mentioned isolation layer, silicidation of source/drain electrodemay be performed to reduce resistance. The silicidation of source/drainelectrode refers to forming a layer of metal silicide on the substrate100 prior to forming the isolation layer. In a specific embodiment, Nior NiPt may be deposited on the substrate 100 first, and NiSi or NiPtSiis formed by annealing, and then the unreacted metal is removed.

When forming the isolation layer 106, the sacrificial layer 1003 may beretained to prevent the material of the isolation layer 106 fromentering the recess for accommodating the gate stack. After that, thesacrificial layer 1003 may be removed to release the space in therecess. According to some embodiments, it may be achieved by, forexample, selectively etching the material of the sacrificial layer 1003(for example, nitride).

Next, the gate stack 104 is formed around the outer periphery of thechannel region 102. As shown in FIG. 10, the gate dielectric layer 1041and the gate conductor layer 1042 may be deposited sequentially on thestructure shown in FIG. 9 (in which the sacrificial layer 1003 has beenremoved), and the gate stack 104 may be formed by etching the gateconductor 1042. The gate dielectric layer 1041 may include an interfacelayer (such as SiO₂) and a high-k material layer (such as HfO₂). In aspecific embodiment, an ALD process may be used to form or deposit aSiO₂ layer (about 0.3 nm˜1.5 nm) and deposit an HfO₂ layer (about 1 nm˜5nm) on the top surface of the isolation layer 106 and in the recess.When etching the gate conductor layer 1042, it is preferable to controlthe top surface of the gate conductor layer 1042 between the uppersurface and the lower surface of the spacer 105 in the secondsource/drain region exposed from the outer peripheral surface of theactive region. At the same time, it is ensured that the gate stack 104formed is not too thin, so that the resistance of the gate stack 104 iscontrolled. In addition, a work function adjustment layer may be furtherformed between the gate dielectric layer 1041 and the gate conductorlayer 1042, which will not be repeated here.

Next, the shape of the gate stack 104 may be adjusted to facilitatesubsequent interconnection production. As shown in FIG. 11, according tosome embodiments, the photoresist 1005 may be formed on the structureshown in FIG. 10. The photoresist 1005 is patterned, for example, byphotolithography, to cover a portion of the gate stack 104 exposedoutside the recess (in this example, the left half in the figure), andalso the other portion of the gate stack 104 exposed outside the recess(in this example, the right half in the figure). Then, the selectiveetching such as RIE may be performed on the gate stack 104 by using thephotoresist 1005 as a mask. In this way, in addition to the portion ofthe gate stack 104 remaining in the recess, the portion of the gatestack 104 covered by the photoresist 1005 is also retained, as shown inFIG. 12. Subsequently, an electrical connection to the gate stack 104may be achieved through this portion. After the etching is completed,the photoresist 1005 is removed.

Next, referring back to FIG. 1, an interlayer dielectric layer 107 isformed on the structure shown in FIG. 12. For example, the interlayerdielectric layer 107 may be formed by depositing an oxide and performinga planarization such as CMP on the deposited oxide. In the interlayerdielectric layer 107, the contacts 108_2 and 108_3 to the firstsource/drain region 101 and the second source/drain region 103 and thecontact 108_1 to the gate stack 104 may be formed respectively. Thesecontacts may be formed by forming via holes by etching in the interlayerdielectric layer 107 and the isolation layer 106 and filling the viaholes with conductive materials such as metal.

Since the gate stack 104 extends beyond the outer periphery of theactive region, the contact 108_1 may be easily formed. In addition,since the lower portion of the first source/drain region 101 extendsbeyond the outer periphery of the columnar active region, that is, thereis no gate stack 104 at least over a portion of the first source/drainregion 101, the contact 108_2 may be easily formed.

FIGS. 13-16 show schematic diagrams of a process of manufacturing asemiconductor device according to another embodiment of the presentdisclosure, in which the process steps same as those in the foregoingembodiment are omitted.

After the channel region 102 (referring to FIG. 4) is formed accordingto the process steps of the foregoing embodiments, a third materiallayer is formed on the structure formed. As shown in FIG. 13, a thirdmaterial layer 1006 is formed on the top surface of the substrate 100,the outer surface of the second material layer 1002 and the outerperipheral surface of the channel region 102. According to someembodiments, the third material layer 1006 may be formed by depositingon the top surface of the substrate 100, the outer surface of the secondmaterial layer 1002 and the outer peripheral surface of the channelregion 102 or by an epitaxial growth process. The material forming thethird material layer 1006 may have a greater etch selectivity ratio thanthe substrate 100, the channel region 102 (the first material layer1001) and the second material layer 1002. According to some embodiments,the third material layer 1006 may employs SiGe with a Ge percentagegreater than that of the first material layer (SiGe). According to someembodiments, the third material layer 1006 may also employs a materialhaving an oxidation rate greater than that of the material forming thesubstrate 100 and the second material layer 1002, such as Ge. theembodiments of the present disclosure is not limited to this, and othermaterials may be used, as long as the etch selectivity of the thirdmaterial layer 1006 relative to the substrate 100, the channel region102 and the second material layer 1002 is ensured.

Next, the sacrificial layer 1003 is formed in the recess formed in FIG.13. In a specific embodiment, a material layer for forming thesacrificial layer 1003 is first deposited on the structure shown in FIG.13. Then, the etching back such as RIE is performed on the depositedmaterial layer so as to form the sacrificial layer 1003. The directionof the etching back is substantially perpendicular to the direction ofthe top surface of the substrate 100. The sacrificial layer 1003 formedis filled in the recesses, and the outer peripheral surface of thesacrificial layer 1003 is substantially coplanar with the outerperipheral surface of the columnar active region, as shown in FIG. 14.According to some embodiments, the sacrificial layer 1003 can be made ofa nitride material. In one hand, the use of nitride material may preventthe sacrificial layer 1003 from being oxidized in the subsequentoxidation process. If the sacrificial layer 1003 is oxidized in thesubsequent oxidation process and thus a portion thereof is etched away,the sacrificial layer 1003 will not be able to completely fill therecesses, and the spacers 105 formed will be damaged by subsequentprocesses. On the other hand, the nitride may ensure that thesacrificial layer 1003 has an etch selectivity relative to othermaterials in the subsequent process, so that the sacrificial layer 1003can be removed by etching without damage to other structures. However,the present disclosure is not limited to this, and other materials withthe above-mentioned characteristics may also be used.

Next, as shown in FIG. 15, the third material layer 1006 is oxidized toform an oxide layer 1007. Since the oxidation rate of the materialforming the third material layer 1006 is greater than the oxidation rateof the material forming the substrate 100 and the second material layer1002, the oxidation treatment almost occurs at the position of the thirdmaterial layer 1006 formed. Similarly, since the third material layer1006 can be oxidized faster, the oxidation reaction may advance alongthe third material layer 1006 between the substrate 100 and thesacrificial layer 1003 and the third material layer 1006 between thesecond material layer 1002 and the sacrificial layer 1003 to the insideof the active region, thereby forming the oxide layer 1007 between thesubstrate 100 and the sacrificial layer 1003 and between the secondmaterial layer 1002 and the sacrificial layer 1003, respectively. Asshown in FIG. 15, the cross section of the oxide layer 1007 also has ashape of a bird's beak.

Next, the oxide layer 1007 is etched to form the spacers 105 at theinterface between the substrate 100 and the sacrificial layer 1003 andbetween the second material layer 1002 and the sacrificial layer 1003,as shown in FIG. 16. Similar to the foregoing embodiments, partialetching may be performed, and remaining unetched oxide layer 1007 isused to form the spacers 105. The oxide layer 1007 formed may also becompletely removed by selective etching, and the spacers 105 may beformed by filling the formed trenches with a material with a lowdielectric constant. The specific process steps may refer to theforegoing embodiments, which will not be repeated here.

The subsequent process steps of manufacturing the semiconductor devicemay be continued with reference to the processing method of theforegoing embodiments, which will not be repeated here.

According to some embodiments of the present disclosure, the thirdmaterial layer 1006 is used to form the oxide layer 1007. Since thethird material layer 1006 may select a material that is easier to beoxidized and has a lower dielectric constant, it is beneficial to speedup the oxidation process and is conducive to reducing the parasiticcapacitance. In addition, the use of the third material layer 1006 toform the oxide layer 1007 may guide the location where oxidation occurs,and better control the oxidation process, thereby improving the qualityof the device.

The semiconductor device according to the embodiments of the presentdisclosure is applicable to various electronic devices. For example, byintegrating a plurality of such semiconductor devices and other devices(for example, other forms of transistors, etc.), it is possible to forman integrated circuit (IC) and thereby construct an electronic device.Therefore, the present disclosure further provides an electronic deviceincluding the above-mentioned semiconductor device. The electronicdevice may further include components such as a display screen matchedwith the integrated circuit and a wireless transceiver matched with theintegrated circuit. Such electronic device includes smart phone,computer, tablet computer (PC), wearable smart device, mobile powersupply, and so on.

In the above description, the technical details such as patterning andetching of each layer have not been described in detail. However, thoseskilled in the art should understand that various technical means may beused to form layers, regions, etc. of desired shapes. In addition, inorder to form the same structure, those skilled in the art may alsodesign a method that is not completely the same as the method describedabove. In addition, although the respective embodiments are describedabove separately, this does not mean that the measures in the respectiveembodiments cannot be advantageously used in combination.

The embodiments of the present disclosure have been described above.However, these embodiments are for illustrative purposes only, and arenot intended to limit the scope of the present disclosure. The scope ofthe present disclosure is defined by the appended claims and theirequivalents. Without departing from the scope of the present disclosure,those skilled in the art can make various substitutions andmodifications, and these substitutions and modifications should all fallwithin the scope of the present disclosure.

1. A semiconductor device, comprising: a substrate; an active regioncomprising a first source/drain region, a channel region and a secondsource/drain region stacked sequentially on the substrate and adjacentto each other; a gate stack formed around an outer periphery of thechannel region; and spacers formed around the outer periphery of thechannel region, respectively between the gate stack and the firstsource/drain region and between the gate stack and the secondsource/drain region; wherein the spacers each have a thickness varyingin a direction parallel to a top surface of the substrate.
 2. Thesemiconductor device according to claim 1, wherein the spacers each havethe thickness gradually decreasing from a surface exposed on an outerperipheral surface of the active region to an inside of the activeregion.
 3. The semiconductor device according to claim 2, wherein thespacers are located outside the outer periphery of the channel region.4. The semiconductor device according to claim 1, wherein the spacerscomprise an oxide.
 5. The semiconductor device according to claim 4,wherein the oxide comprises an oxide formed by oxidizing a material ofthe first source/drain region and the second source/drain region.
 6. Thesemiconductor device according to claim 4, wherein the oxide comprisesan oxide formed by oxidizing a material deposited on a surface of thefirst source/drain region and/or the second source/drain region.
 7. Thesemiconductor device according to claim 5, wherein the spacers comprisea material with a low dielectric constant.
 8. The semiconductor deviceaccording to claim 7, wherein the material with the low dielectricconstant comprises SiC.
 9. The semiconductor device according to claim1, wherein a doped region of the first source/drain region and a dopedregion of the second source/drain region extend along an outer surfaceof the first source/drain region and an outer surface of the secondsource/drain region respectively.
 10. The semiconductor device accordingto claim 1, wherein the spacers are located inside the doped region ofthe first source/drain region and the doped region of the secondsource/drain region respectively.
 11. The semiconductor device accordingto claim 10, wherein a bottom surface of the gate stack is substantiallyparallel to an interface between a material layer forming the channelregion and a material layer forming the first source/drain region, and atop surface of the gate stack is substantially parallel to an interfacebetween the material layer forming the channel region and a materiallayer forming the second source/drain region.
 12. The semiconductordevice according to claim 11, wherein a distance between the bottomsurface of the gate stack and the interface between the material layerforming the channel region and the material layer forming the firstsource/drain region is substantially equal to a distance between the topsurface of the gate stack and the interface between the material layerforming the channel region and the material layer forming the secondsource/drain region.
 13. The semiconductor device according to claim 1,wherein the channel region comprises a single crystal semiconductormaterial.
 14. The semiconductor device according to claim 1, wherein asemiconductor material of the channel region is different from asemiconductor material of the first source/drain region and/or thesecond source/drain region.
 15. A method of manufacturing asemiconductor device, comprising: forming a first material layer and asecond material layer sequentially on a substrate; defining an activeregion of the semiconductor device on the substrate, the first materiallayer and the second material layer, wherein the active region comprisesa channel region; forming spacers around an outer periphery of thechannel region, respectively at set positions of the substrate and thesecond material layer; forming a first source/drain region and a secondsource/drain region on the substrate and the second material layerrespectively; and forming a gate stack around the outer periphery of thechannel region; wherein the spacers each have a thickness varying in adirection parallel to a top surface of the substrate.
 16. The methodaccording to claim 15, wherein the defining an active region of thesemiconductor device on the substrate, the first material layer and thesecond material layer comprises: sequentially etching the secondmaterial layer, the first material layer and an upper portion of thesubstrate to form a columnar active region, and extending a lowerportion of the substrate beyond an outer periphery of the columnaractive region; and selectively etching the first material layer so thatthe first material layer is recessed inward relative to the outerperiphery of the columnar active region so as to form the channelregion.
 17. The method according to claim 16, wherein the formingspacers around an outer periphery of the channel region, respectively atset positions of the substrate and the second material layer comprises:forming a sacrificial layer in the recess; oxidizing the top surface ofthe substrate and the outer surface of the second material layer so asto form an oxide layer on the top surface of the substrate, the outersurface of the second material layer, the interface between thesubstrate and the sacrificial layer, and the interface between thesecond material layer and the sacrificial layer; and etching the oxidelayer so as to use unetched oxide layer to form the spacers at theinterface between the substrate and the sacrificial layer and theinterface between the second material layer and the sacrificial layer.18. The method according to claim 17, wherein, when oxidizing the topsurface of the substrate and the outer surface of the second materiallayer, a process of the oxidizing is controlled so that the spacersformed at the interface between the substrate and the sacrificial layerand the interface between the second material layer and the sacrificiallayer are located outside the outer periphery of the channel region. 19.The method according to claim 16, wherein the forming spacers around anouter periphery of the channel region, respectively at set positions ofthe substrate and the second material layer comprises: forming a thirdmaterial layer on the top surface of the substrate, an outer surface ofthe second material layer and an outer peripheral surface of the channelregion, wherein a material of the third material layer has an oxidationrate greater than that of materials of the substrate, the first materiallayer and the second material layer; forming a sacrificial layer in therecess where the third material layer is formed; oxidizing the thirdmaterial layer to form an oxide layer; and etching the oxide layer so asto use unetched oxide layer to form the spacers between the substrateand the sacrificial layer and between the second material layer and thesacrificial layer respectively.
 20. The method according to claim 17,wherein subsequent to forming the oxide layer by oxidation treatment,the method further comprises: selectively etching the oxide layer tocompletely remove the oxide layer so as to form trenches between thesubstrate and the sacrificial layer and between the second materiallayer and the sacrificial layer respectively; and filling the trenchesso as to form the spacers in the trenches.
 21. The method according toclaim 16, wherein the selectively etching comprises: using a modifier atleast once to form a modified layer on a surface comprising the surfaceto be etched; and etching the modified layer at least once to form apredetermined structure on the surface to be etched.
 22. The methodaccording to claim 17, wherein the forming a first source/drain regionand a second source/drain region on the substrate and the secondmaterial layer respectively comprises: depositing a dopant film on theouter surface of the columnar active region at least comprising asurface of the upper portion of the substrate and the outer surface ofthe second material layer; annealing to drive in a diffusion of thedopant film so as to form the first source/drain region and the secondsource/drain region on the upper portion of the substrate and on thesecond material layer respectively; and removing the dopant film. 23.The method according to claim 22, wherein when annealing to drive in thediffusion of the dopant film, a process of the diffusion is controlledso that the spacers are located inside the doped region of the firstsource/drain region and the doped region of the second source/drainregion respectively.
 24. The method according to claim 17, wherein theforming a gate stack around an outer periphery of the channel regioncomprises: removing the sacrificial layer, or removing the sacrificiallayer and un-oxidized third material layer sequentially; depositing agate dielectric layer and a gate conductor layer sequentially; andetching back the gate dielectric layer and the gate conductor layer soas to form the gate stack around the outer periphery of the channelregion.
 25. An electronic device, comprising an integrated circuitformed by the semiconductor device according to claim
 1. 26. Theelectronic device according to claim 25, wherein the electronic devicecomprises a smart phone, a computer, a tablet computer, an artificialintelligence device, a wearable device, or a mobile power supply.